From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nishanth Menon Subject: Re: [PATCH 1/3] mfd: twl6040: Select i2c fast mode as default with regmap patch Date: Thu, 27 Feb 2014 08:24:04 -0600 Message-ID: <530F4A84.9070906@ti.com> References: <1393509410-1640-1-git-send-email-peter.ujfalusi@ti.com> <1393509410-1640-2-git-send-email-peter.ujfalusi@ti.com> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1393509410-1640-2-git-send-email-peter.ujfalusi@ti.com> Sender: linux-kernel-owner@vger.kernel.org To: Peter Ujfalusi , Lee Jones Cc: florian.vaussard@epfl.ch, linux-kernel@vger.kernel.org, linux-omap@vger.kernel.org, Samuel Ortiz List-Id: linux-omap@vger.kernel.org On 02/27/2014 07:56 AM, Peter Ujfalusi wrote: > All boards using twl6040 configures the i2c bus to 400KHz. While twl6040's > defaults to normal mode (100KHz). So far twl6040 has no problem with i2c > communication in this configuration it is safer to select fast i2c mode. > > Signed-off-by: Peter Ujfalusi > --- > drivers/mfd/twl6040.c | 9 +++++++-- > include/linux/mfd/twl6040.h | 1 + > 2 files changed, 8 insertions(+), 2 deletions(-) > > diff --git a/drivers/mfd/twl6040.c b/drivers/mfd/twl6040.c > index 6e88f25832fb..2c308750f40f 100644 > --- a/drivers/mfd/twl6040.c > +++ b/drivers/mfd/twl6040.c > @@ -87,8 +87,13 @@ static struct reg_default twl6040_defaults[] = { > }; > > static struct reg_default twl6040_patch[] = { > - /* Select I2C bus access to dual access registers */ > - { TWL6040_REG_ACCCTL, 0x09 }, > + /* > + * Select I2C bus access to dual access registers > + * Interrupt register is cleared on read > + * Select fast mode for i2c (400KHz) > + */ > + { TWL6040_REG_ACCCTL, > + TWL6040_I2CSEL | TWL6040_INTCLRMODE | TWL6040_I2CMODE(1) }, > }; > > > diff --git a/include/linux/mfd/twl6040.h b/include/linux/mfd/twl6040.h > index 81f639bc1ae6..a69d16b30c18 100644 > --- a/include/linux/mfd/twl6040.h > +++ b/include/linux/mfd/twl6040.h > @@ -157,6 +157,7 @@ > #define TWL6040_I2CSEL 0x01 > #define TWL6040_RESETSPLIT 0x04 > #define TWL6040_INTCLRMODE 0x08 > +#define TWL6040_I2CMODE(x) ((x & 0x3) << 4) > > /* STATUS (0x2E) fields */ > > we should ideally have been using highspeed for i2c bus. is'nt it better if i2c_check_functionality (and adding required flags for func) be used to check the adapter speed and decide this in the driver instead of hardcoding the bus speed within TWL6040 - considering that 6040 can infact do max high speed as well? -- Regards, Nishanth Menon